Actually, we require *CUDA 5.5* due to driver bugs at least with the `sm_35` architecture. But one *can* use cuda 5.0 with cuda-5.5-like drivers.

@psychocoderHPC Knows why we need CUDA 5.0+ itself. I have in mind some minor features/bugs required updating (at least today, I recognised compile errors with cuda 4.2 + recent boost versions).